U.S. patent number 9,541,867 [Application Number 14/840,765] was granted by the patent office on 2017-01-10 for apparatus, method, and non-transitory recording medium for power generation using heat in image forming apparatus.
This patent grant is currently assigned to Rioch Company, Ltd.. The grantee listed for this patent is Homare Ehara, Takuma Kasai, Ryohta Kubokawa, Keita Maejima, Norikazu Okada, Takaaki Shirai, Tomoyuki Yamashita. Invention is credited to Homare Ehara, Takuma Kasai, Ryohta Kubokawa, Keita Maejima, Norikazu Okada, Takaaki Shirai, Tomoyuki Yamashita.
United States Patent |
9,541,867 |
Ehara , et al. |
January 10, 2017 |
Apparatus, method, and non-transitory recording medium for power
generation using heat in image forming apparatus
Abstract
An image forming apparatus includes a fixing device to fix an
image on a recording medium by heating the recording medium,
multiple heat storing devices to store heat generated at the fixing
device, an electric generating element to generate power by
converting the heat into power, and a switch to switch connection
and disconnection between the electric generating element and at
least one of the multiple heat storing devices.
Inventors: |
Ehara; Homare (Kanagawa,
JP), Shirai; Takaaki (Tokyo, JP), Okada;
Norikazu (Kanagawa, JP), Yamashita; Tomoyuki
(Kanagawa, JP), Kubokawa; Ryohta (Kanagawa,
JP), Kasai; Takuma (Kanagawa, JP), Maejima;
Keita (Kanagawa, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Ehara; Homare
Shirai; Takaaki
Okada; Norikazu
Yamashita; Tomoyuki
Kubokawa; Ryohta
Kasai; Takuma
Maejima; Keita |
Kanagawa
Tokyo
Kanagawa
Kanagawa
Kanagawa
Kanagawa
Kanagawa |
N/A
N/A
N/A
N/A
N/A
N/A
N/A |
JP
JP
JP
JP
JP
JP
JP |
|
|
Assignee: |
Rioch Company, Ltd. (Tokyo,
JP)
|
Family
ID: |
55454675 |
Appl.
No.: |
14/840,765 |
Filed: |
August 31, 2015 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160077475 A1 |
Mar 17, 2016 |
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Foreign Application Priority Data
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Sep 16, 2014 [JP] |
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2014-187696 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03G
15/2039 (20130101); G03G 15/2017 (20130101); G03G
15/80 (20130101) |
Current International
Class: |
G03G
15/20 (20060101); G03G 15/00 (20060101) |
Field of
Search: |
;399/328,69,88 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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201654576 |
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Nov 2010 |
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CN |
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2008040235 |
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Feb 2008 |
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JP |
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2011-059273 |
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Mar 2011 |
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JP |
|
Other References
Computer translation of JP2011-059273A, Apr. 2011 to Yamaguchi;
cited by applicant computer translation of JP2008-040235A, Feb.
2008 to Kudo. cited by examiner .
U.S. Appl. No. 14/745,828, filed Jun. 22, 2015. cited by
applicant.
|
Primary Examiner: Grainger; Quana M
Attorney, Agent or Firm: Harness, Dickey & Pierce,
P.L.C.
Claims
What is claimed is:
1. An image forming apparatus comprising: a fixing device
configured to fix an image on a recording medium by heating the
recording medium; an electric generating element configured to
generate power by converting the heat into power; multiple heat
storing devices configured to store heat generated at the fixing
device and configured to supply the heat stored to the electric
generating element; and a switch configured to switch connection
and disconnection between the electric generating element and at
least one of the multiple heat storing devices.
2. The image forming apparatus according to claim 1, further
comprising an acquisition device configured to acquire setting
information for use in image forming conducted by the image forming
apparatus and a control device to control the connection and
disconnection by the switch based on the setting information
acquired by the acquisition device.
3. The image forming apparatus according to claim 2, further
comprising: a storing device configured to store a temperature
distribution of the fixing device linked with the setting
information, wherein the control device is configured to acquire
the temperature distribution of the fixing device corresponding to
the setting information from the storing device and changes the
connections and disconnections of the switch based on the
temperature distribution to make power generation efficiency of the
power generating element higher.
4. The image forming apparatus according to claim 2, further
comprising a storing device configured to store temperature
distribution linking information in which the setting information
is linked with a temperature distribution of the fixing device
obtained after image forming is conducted, wherein, based on the
temperature distribution linking information and the setting
information acquired by the acquisition device, the control device
is configured to calculate an expected temperature distribution of
the fixing device after image forming is conducted according to the
setting information acquired by the acquisition device and
configured to change the connections and disconnections of the
switch based on the expected temperature distribution to make power
generation efficiency of the power generating element higher.
5. The image forming apparatus according to claim 2, wherein the
setting information includes information of the recording medium
for use in the image forming.
6. The image forming apparatus according to claim 2, further
comprising: a storing device configured to store temperature
distribution linking information in which a combination of the
setting information and an amount of toner for use in an image
fixed on the recording medium is linked with a temperature
distribution of the fixing device obtained after image forming is
conducted, wherein, based on the temperature distribution linking
information, the setting information acquired by the acquisition
device, and image data of the image to be formed on the recording
medium, the control device is configured to calculate an expected
temperature distribution of the fixing device after image forming
is conducted according to the setting information acquired by the
acquisition device and configured to change the connections and
disconnections of the switch based on the expected temperature
distribution to make power generation efficiency of the power
generating element higher.
7. The image forming apparatus according to claim 4, wherein, based
on the setting information acquired by the acquisition device and
the temperature distribution linking information, the control
device is configured to calculate an expected change of the
temperature distribution of the fixing device over time after image
forming is conducted according to the setting information acquired
by the acquisition device and configured to change the connections
and disconnections of the switch based on the expected change of
the temperature distribution to make power generation efficiency of
the power generating element higher.
8. The image forming apparatus according to claim 2, wherein the
fixing device includes multiple heaters having different heating
ranges to heat the fixing device, wherein the image forming
apparatus further includes a storing device configured to store
temperature distribution linking information in which a combination
of the setting information and usage status of the multiple heaters
to heat the fixing device is linked with a temperature distribution
of the fixing device obtained after image forming is conducted, and
wherein, based on the temperature distribution linking information,
the setting information acquired by the acquisition device, and
information on which of the multiple heaters is used when image
forming is conducted according to the setting information, the
control device is configured to calculate an expected temperature
distribution of the fixing device after image forming is conducted
according to the setting information acquired by the acquisition
device and configured to change the connections and disconnections
of the switch based on the expected temperature distribution to
make power generation efficiency of the power generating element
higher.
9. An image forming method, comprising: acquiring setting
information indicating a content of image forming conducted by an
image forming apparatus including a fixing device to heat a
recording medium to fix an image thereon, an electric generating
element to generate power by converting the heat into power,
multiple heat storing devices to store heat generated at the fixing
device and supply the heat stored to the electric generating
element, and a switch to switch connection and disconnection
between the electric generating element and at least one of the
multiple heat storing devices; and controlling switching the
connection and the disconnection by a switch based on the setting
information acquired in the step of acquiring setting
information.
10. A non-transitory recording medium which, when executed by one
or more processors, perform an image forming method, comprising the
steps of: acquiring setting information indicating a content of
image forming conducted by an image forming apparatus including a
fixing device to heat a recording medium to fix an image thereon,
an electric generating element to generate power by converting the
heat into power, multiple heat storing devices to store heat
generated at the fixing device and supply the heat stored to the
electric generating element, and a switch to switch connection and
disconnection between the electric generating element and at least
one of the multiple heat storing devices; and controlling switching
the connection and the disconnection by a switch based on the
setting information acquired by the step of acquiring setting
information.
11. The image forming apparatus according to claim 1, wherein the
multiple heat storing devices are provided along a longitudinal
direction of the fixing device and include a first heat storing
device and a second heat storing device provided inside of the
fixing device in the longitudinal direction, and wherein the switch
switches connection and disconnection between the electric
generating element and at least the second heat storing device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This patent application is based on and claims priority pursuant to
35 U.S.C. .sctn.119(a) to Japanese Patent Application No.
2014-187696, filed on Sep. 16, 2014 in the Japan Patent Office, the
entire disclosure of which is hereby incorporated by reference
herein.
BACKGROUND
Technical Field
The present invention relates to an image forming apparatus, an
image forming method, and a non-transitory recording medium.
Description of the Related Art
There is a group of technologies to generate power in an image
forming apparatus using extra heat generated in the fixing device
therein to fix a toner image, etc. on a recording medium, typically
paper.
SUMMARY
According to the present invention, provided is an improved image
forming apparatus which includes a fixing device to fix an image on
a recording medium by heating the recording medium, multiple heat
storing devices to store heat generated at the fixing device, an
electric generating element to generate power by converting the
heat into power, and a switch to switch connection and
disconnection between the electric generating element and at least
one of the multiple heat storing devices.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
Various other objects, features and attendant advantages of the
present invention will be more fully appreciated as the same
becomes better understood from the detailed description when
considered in connection with the accompanying drawings in which
like reference characters designate like corresponding parts
throughout and wherein:
FIG. 1 is a cross section illustrating a schematic configuration of
an image forming apparatus according to an embodiment of the
present disclosure;
FIG. 2 is a block diagram illustrating the configuration of the
image forming apparatus illustrated in FIG. 1 based on the fixing
device and the power system therein;
FIG. 3 is a graph illustrating current-voltage characteristics of a
thermoelectric generating element;
FIG. 4 is a graph illustrating temperature-power generation
characteristics of a thermoelectric generating element;
FIG. 5 is a diagram illustrating a charging path in the image
forming apparatus illustrated in FIG. 2;
FIG. 6 is a diagram illustrating a heat supply status to a power
generating element in Comparative Examples of the present
disclosure described later;
FIG. 7 is a diagram illustrating the configuration of a heat
storing plate in the image forming apparatus illustrated in FIG. 1
and a heat supply status to a power generating element when a
second heat storing plate is separated from the power generating
element;
FIG. 8 is a graph illustrating power generated by the power
generating element when the heat is stored in the state of FIG. 6
and FIG. 7;
FIG. 9 is a diagram illustrating an example of the heat supplying
status to a power generating element when a second heat storing
plate is separated from the power generating element while the
image forming apparatus stands by;
FIG. 10 is a diagram illustrating an example of the heat supplying
status to a power generating element when a second heat storing
plate is connected with the power generating element while the
image forming apparatus stands by as illustrated in FIG. 9;
FIG. 11 is a graph illustrating generated power when the heat is
stored in the state of FIG. 9 and FIG. 10;
FIG. 12 is a diagram illustrating an example of the heat supplying
status to a power generating element when a second heat storing
plate is separated from the power generating element after printing
images on ten sheets of B5 size transfer paper;
FIG. 13 is a diagram illustrating an example of the heat supplying
status to a power generating element when a second heat storing
plate is connected with the power generating element after printing
images as illustrated in FIG. 12;
FIG. 14 is a graph illustrating generated power when the heat is
stored in the state of FIG. 12 and FIG. 13;
FIG. 15 is a diagram illustrating an example of the heat supplying
status to a power generating element when a second heat storing
plate is separated from the power generating element after printing
images on 100 sheets of B5 size transfer paper;
FIG. 16 is a diagram illustrating an example of the heat supplying
status to a power generating element when a second heat storing
plate is connected with the power generating element after printing
images as illustrated in FIG. 15;
FIG. 17 is a graph illustrating generated power when the heat is
stored in the state of FIG. 15 and FIG. 16;
FIG. 18 is a diagram illustrating an example of the heat supply
status to a power generating element when a second heat storing
plate is separated from the power generating element after printing
images on B5 size transfer paper;
FIG. 19 is a diagram illustrating an example of the heat supply
status to a power generating element when a second heat storing
plate is connected with the power generating element after printing
images as illustrated in FIG. 18;
FIG. 20 is a graph illustrating generated power when the heat is
stored in the state of FIG. 18 and FIG. 19;
FIG. 21 is a diagram illustrating an example of the heat supply
status to a power generating element when a second heat storing
plate is separated from the power generating element after printing
images on A4 size transfer paper;
FIG. 22 is a diagram illustrating an example of the heat supply
status to a power generating element when a second heat storing
plate is connected with the power generating element after printing
images as illustrated in FIG. 21;
FIG. 23 is a graph illustrating generated power when the heat is
stored in the state of FIG. 21 and FIG. 22;
FIG. 24 is a table illustrating a storing state of the temperature
distribution profiles in the image forming apparatus illustrated in
FIG. 1;
FIG. 25 is a flow chart illustrating control processing about
separation and installation of a heat storing plate conducted by
the control device of the image forming apparatus illustrated in
FIG. 1;
FIG. 26 is a table illustrating a storing state of the temperature
distribution profiles in a variation example, corresponding to the
table illustrated in FIG. 24;
FIG. 27 is a table illustrating a storing state of the temperature
distribution profiles in another variation example, corresponding
to the table illustrated in FIG. 24; and
FIG. 28 is a table illustrating a storing state of the temperature
distribution profiles in yet another variation example,
corresponding to the table illustrated in FIG. 24.
The accompanying drawings are intended to depict example
embodiments of the present invention and should not be interpreted
to limit the scope thereof. The accompanying drawings are not to be
considered as drawn to scale unless explicitly noted.
DETAILED DESCRIPTION
The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the present invention. As used herein, the singular forms "a", "an"
and "the" are intended to include the plural forms as well, unless
the context clearly indicates otherwise. It will be further
understood that the terms "includes" and/or "including", when used
in this specification, specify the presence of stated features,
integers, steps, operations, elements, and/or components, but do
not preclude the presence or addition of one or more other
features, integers, steps, operations, elements, components, and/or
groups thereof.
In describing example embodiments shown in the drawings, specific
terminology is employed for the sake of clarity. However, the
present disclosure is not intended to be limited to the specific
terminology so selected and it is to be understood that each
specific element includes all technical equivalents that operate in
a similar manner.
In the following description, illustrative embodiments will be
described with reference to acts and symbolic representations of
operations (e.g., in the form of flowcharts) that may be
implemented as program modules or functional processes including
routines, programs, objects, components, data structures, etc.,
that perform particular tasks or implement particular abstract data
types and may be implemented using existing hardware at existing
network elements or control nodes. Such existing hardware may
include one or more Central Processing Units (CPUs), digital signal
processors (DSPs), application-specific-integrated-circuits, field
programmable gate arrays (FPGAs) computers or the like. These terms
in general may be referred to as processors.
Unless specifically stated otherwise, or as is apparent from the
discussion, terms such as "processing" or "computing" or
"calculating" or "determining" or "displaying" or the like, refer
to the action and processes of a computer system, or similar
electronic computing device, that manipulates and transforms data
represented as physical, electronic quantities within the computer
system's registers and memories into other data similarly
represented as physical quantities within the computer system
memories or registers or other such information storage,
transmission or display devices.
According to the present disclosure, power can be generated with a
high level of efficiency even when the temperature of a fixing
device is uneven.
Next, embodiments of the present disclosure are described with
reference to accompanying drawings.
FIG. 1 is a cross section illustrating a schematic configuration of
an image forming apparatus according to an embodiment of the
present disclosure.
An image forming apparatus 10 illustrated in FIG. 1 is a digital
multifunction peripheral (MFP) having various image processing
features such as photocopying features, printing features, and
facsimile features. In addition, an application switching key on
the operation unit, the photocopying features, the printing
features, and the facsimile features are sequentially switchable.
The image forming apparatus 10 conducts processing based on the
mode selected.
Incidentally, the image forming apparatus 10 can have one or more
of these features.
With regard to the features of the image forming apparatus 10,
operations on photocopying mode are described in detail.
In the photocopying mode, by an automatic document feeder 101,
documents are sequentially fed to an image reader 102, where image
information is read. The image information is converted into
optical information by a writing unit 103 serving as a writing
device via an image processing device. A drum image bearer 104 is
uniformly charged by a charger and thereafter irradiated (exposed)
according to the optical information from the writing unit 103 to
form a latent electrostatic image thereon. The latent electrostatic
image formed on the drum image bearer 104 is developed by the
developing device 105 to form a toner image.
The toner image is transferred to transfer paper by a transfer belt
106. The toner image is fixed on the transfer paper by a fixing
device 107 and transfer paper is ejected. As a consequence, images
are printed on transfer paper serving as a recording medium by
electrophotography.
A printer unit 108 is to transfer the same image as an original
read according to optical information converted at the writing unit
103 to a recording medium and includes the drum image bearer 104,
the developing device 105, the transfer belt 106, and the fixing
device 107.
A capacitor unit 108 includes a condenser (storage battery 118)
serving as a storing device) and stores electricity obtained by
electric generation by the thermoelectric converter to supply the
stored electricity to each unit. The condenser stores charges as
electricity by application of a voltage. The condenser is just an
example. Other storage devices such as a storage battery to store
electricity utilizing chemical reaction can be also used.
Next, FIG. 2 is a diagram illustrating the fixing device 107, which
is provided to the image forming apparatus 10, other devices
adjacent thereto, and the power system connected to those
devices.
As illustrated in FIG. 2, the image forming apparatus 10 has the
fixing device 107, a fixing roller 107a, power generating elements
110, first heat storing plates 111, second heat storing plates 112,
switches 112a, coolers 113, a temperature detecting element 114, a
control device 115, a temperature control device 115a, a memory
116, a DC/AC converter 117 having a maximum power point tracking
(MPPT) feature, a storage battery 118, a discharging circuit 119, a
switching circuit 120, a load 121, a power supply unit (PSU) 122,
and a fixing drive circuit 122a. PSU 122 is connected to a
commercial power source 123.
Of these, the fixing device 107 fixes an image on a recording
medium upon application of heat and pressure thereto by the fixing
roller 107a having a heater 107b. The heater 107b heats the fixing
roller 107a.
The power generating elements 110 generate power by a
thermoelectric conversion element that converts heat energy to
electric energy and provided to close to each end of the fixing
roller 107a. The thermoelectric conversion element can be arbitrary
thermoelectric conversion element, for example, typically used
thermoelectric conversion element utilizing Seebeck effect.
In addition, heat storing members are provided at both ends of the
fixing roller 107a to store the heat of the surface of the fixing
roller 107a. The heat storing member is provided to efficiently
transfer heat to the power generating elements 110 and composed of
materials having large heat conductivity. The materials are not
particularly limited. Metal materials such as aluminum or copper or
a heat pipe are preferable. In the present disclosure, a pair of
the first heat storing plates 111 and a pair of the second heat
storing plates 112 are provided as an example of the heat storing
members. At each end, the first heat storing plates 111 are
arranged at the outer side and, the second heat storing plates 112,
at the inner side.
Each of the first heat storing plates 111 and the second heat
storing plates 112 is connected to the HOT surface of the power
generating element 110 to store heat of the fixing roller 107a and
supply it to the HOT surface. In addition, the switch 112a is
provided between the second heat storing plate 112 and the power
generating element 110 to switch connection and disconnection
therebetween. The switch 112a switches between the high heat
transfer efficiency state (connected) and the low heat transfer
efficiency state (disconnected).
Moreover, the cooler 113 is provided in the vicinity of the COLD
surface of the power generating element 110. This cooler 113 cools
down the COLD surface of the power generating element 110.
The temperature detecting element 114 is provided adjacent to the
fixing roller 107a. This temperature detecting element 114 detects
the temperature of the surface of the fixing roller 107a and
transmits it to the control device 115. Incidentally, the
temperature detecting element 114 measures the temperature of the
surface of the fixing roller 107a at multiple positions along the
axis direction thereof including the positions facing the first
heat storing plates 111 and the second heat storing plates 112.
The control device 115 controls the entire of the image forming
apparatus 10. It sequentially controls operations by executing
programs stored in the memory 116 according to each operation
mode.
The temperature control device 115a provided to the control device
115 controls the output of the heater 107b by controlling the
fixing drive circuit 122a provided to the PSU 122 based on the
temperature transmitted from the temperature detecting element 114
to keep the temperature of the fixing device in desired target
temperatures.
The target temperatures vary depending on the state such as image
forming in process (in particular, fixing) and stand-by.
In addition, the control device 115 makes the memory 116 store the
temperature transition of each portion of the fixing roller 107a
during image forming corresponding to the image forming conditions
such as color or monochrome printing, the identity of transfer
paper (material, size, direction, etc.), a run length. Thereafter,
based on the accumulated information of the temperature transition,
a temperature distribution profile is created for the temperature
distribution of each portion of the fixing roller 107a at the end
of the image forming per image forming condition, which is stored
in the memory 116 pairing (linked with) the image forming
condition. With regard to the condition of the number of printing
sheets (run length), for example, the temperature distribution at
the completion of printing an image on tenth paper for a run length
of 100 sheets can be utilized to deduce the temperature
distribution of the completion of image forming with a run length
of 10 sheets. That is, it is possible to use an image forming
condition having a run length to create a temperature distribution
profile linked with a condition having a different run length.
The memory 116 stores the temperature transition of the surface of
the fixing roller 107a and the temperature distribution profile.
Incidentally, the temperature distribution profile is created based
on the temperature transition as described above and also a user
can store arbitrary data input from outside in the profile.
MPPT 117 is a charging circuit operating when storing energy
generated by the power generating element 110 in the storage
battery 118. MPPT 117 is described in detail in the description of
FIG. 5.
The storage battery 118 accumulates energy generated by the power
generating element 110. The storage battery 118 can be recharged by
other power sources.
The discharging circuit 119 converts the voltage of the power
discharged by the storage battery 118 to a voltage suitable to
drive the load 121.
The switching circuit 120 has a feature to supply a voltage to the
load 121 by switching the power created by the PSU 122 based on the
power supplied from the commercial power source 123 and the power
created by the storage battery 118 and the discharging circuit
119.
The load 121 is a part driven by a power such as a motor.
The PSU 122 converts an AC power source to a DC power source and
supplies it.
The fixing drive circuit 122a adjusts the power supplied to the
heater 107b and is controlled by the temperature control device
115a.
The commercial power source 123 is an alternating current source
supplied from an electric company.
One of the features of the image forming apparatus 10 described
above is that the pair of the first heat storing plates 111 and the
pair of the second heat storing plates to store the heat generated
at the surface of the fixing roller 107a are provided and also
switching devices to open and close the connection of the second
heat scoring plates 112 and the power generating elements 110 are
provided.
This feature is described below.
First, the current-voltage characteristics are described referring
to FIG. 3.
FIG. 3 is a graph illustrating this current-voltage
characteristics. X axis represents voltage and Y axis represents
current.
What is illustrated in FIG. 3 is the relation between the output
voltage and the output current of a thermoelectric generating
element when the temperature difference T between the HOT surface
and the COLD surface thereof is 50 degrees C., 100 degrees C., or
150 degrees C. As seen in FIG. 3, the output of thermoelectric
generating element differs depending on the temperature difference
T. At the same temperature difference, the output current is
constant until the output voltage reaches a certain value but the
output current sharply drops above the certain value. The output
voltage of thermoelectric generating element is maximum at this
"certain value". This maximum voltage is referred to as the optimal
operating voltage point. When this output voltage is applied to
thermoelectric generating element, the power generation efficiency
becomes high.
Next, FIG. 4 is a graph illustrating temperature-power generation
characteristics of a thermoelectric generating element.
In FIG. 4, X axis represents "the temperature difference T between
the HOT surface and the COLD surface of a power generating element"
and Y axis represents generated power per unit area. The
temperature of the COLD surface is kept by the cooler 113. In the
graph illustrated in FIG. 4, the generated power at the optimal
operating voltage point is plotted at each temperature difference T
illustrated in FIG. 3.
According to the graph, the generated power is 10 W when the
temperature difference T is 50 degrees C., the generated power is
40 W when the temperature difference T is 100 degrees C., and the
generated power is 90 W when the temperature difference T is 150
degrees C. As seen in the graph, the generated power per unit area
increases directly with the square of the temperature difference
T.
The behavior of the MPPT 117 provided to the image forming
apparatus 10 is described next with reference to FIG. 5.
FIG. 5 is a diagram illustrating the charging path in the image
forming apparatus 10.
As seen in FIG. 5, the electric energy generated by the power
generating element 110 is stored in the storage battery 118 via the
MPPT 117.
As seen in the current-voltage characteristics illustrated in FIG.
3, the voltage of the power generating element decreases as the
output current increases and the voltage of the power generating
element increases as the output current decreases
Therefore, when the output voltage of the DC/DC converter provided
to the MPPT 117 is intentionally increased, the charging current to
the storage battery increases because the voltage difference with
the storage battery increases. As the consequence, the input
current (current taken out from the power generating element 110)
to the MPPT 117 increases, so that the voltage of the power
generating element drops and vice versa.
Taking advantage of this, by controlling the output voltage of the
DC/DC converter, the power taken out from the power generating
element is increased. The MPPT 117 has a feature of finding out the
optimal operating voltage point of the power generating element 110
based on this and controls the output current (that is, the amount
of charging current) of the DC/DC converter to conduct operations
at this optimal operating voltage point.
The effect obtained by providing the first heat storing plate 111
and the second heat storing plate 112 and having opening and
closing the connection between the first heat storing plate 111 and
the second heat storing plate 112 switchable is described using
several specific examples.
Prior to this, a comparative example is described which includes
only one heat storing plate in the vicinity at each end of the
fixing roller 107a.
FIG. 6 is a diagram illustrating the state of a heat supply to a
power generating element in the comparative example. Incidentally,
in FIG. 6, the same reference numerals are assigned to the
configuration in common with the image forming apparatus 10
described above.
In the comparative example of FIG. 6, as described above, a heat
storing plate 200 having the same area of the total of the first
heat storing plate 111 and the second heat storing plate 112 is
arranged closed to each of both ends of the fixing roller 107a
corresponding to the positions of these two heat storing plates 111
and 112 and connected to the power generating element 110. However,
no switch is provided to this connection. This comparative example
has the same image forming apparatus 10 described above except for
the structure of the heat storing plate 200 and the feature of
opening and closing of the connection.
In addition, in FIG. 6, the solid line A indicates the temperature
distribution profile of the surface of the fixing roller 107a and
the dotted line At indicates the temperature of the heat
transferred to the HOT surface of the power generating element 110
when the heat storing plate 200 is moved closer to the fixing
roller 107a at the state after images are printed on a certain
number of A4 transfer sheets with portrait orientation.
Incidentally, the reference numeral 210 indicates the position
where the transfer sheet passes during image forming.
The comparative example illustrated in FIG. 6 is rather a extreme
case for convenience of description. The transfer sheet deprives
the surface of the fixing roller 107a of heat at the position
indicated by the reference numeral 210 where the transfer sheet has
passed immediately after an image is formed on the transfer sheet.
For this reason, the temperature thereat is lower than the other
portions. In the example illustrated in FIG. 6, the temperature of
the portion (the lower temperature portion) where the transfer
sheet has passed is 110 degrees C. and the temperature at the other
portions (higher temperature portion) is 210 degrees C.
The heat storing plate 200 is located over both areas. Therefore,
the heat storing plate 200 deprives not only the high temperature
portion but also the low temperature portion of heat. The
temperature on the heat supplying plate 200 is uniformed and is 160
degrees C. as indicated by At. The heat of the temperature is
transferred to the HOT surface of the power generating element
110.
Next, FIG. 7 is a diagram illustrating an example of the state of
heat supply to the power generating element 110 in the image
forming apparatus 10 of the embodiment described using FIG. 1,
etc.
This example has the same condition as described in FIG. 6 except
for the heat storing plate. FIG. 7 is a diagram illustrating the
state (switch disconnected) in which the second heat storing plate
112 is separated from the power generating element 110. In
addition, the solid line B indicates the temperature distribution
profile (same as that in FIG. 6) of the surface of the fixing
roller 107a and the dotted line Bt indicates the temperature of the
heat transferred to the HOT surface of the power generating element
110 when the first heat storing plate 111 and the second heat
storing plate 112 are moved closer to the fixing roller 107a at the
state.
In this case, since the first heat storing plate 111 deprives only
the high temperature portion of heat, the heat of 210 degrees C.,
which is same as at the high temperature portion is transferred to
the HOT surface. Incidentally, the solid line B and the dotted line
Bt are shown with a alight difference in height in FIG. 7. This is
to avoid overlapping of both lines. In fact, both lines represents
the same temperature. This is true about the solid lines and the
dotted lines in the figures below.
On the other hand, the second heat storing plate 112 stores the
heat from the low temperature portion but since it is disconnected
from the power generating element 110, the heat is not transferred
to the power generating element 110. This is the reason the dotted
line Bt is not drawn at the position corresponding to the second
heat storing plate 112.
Therefore, in the example of FIG. 7, the heat of 210 degrees C.,
which is not uniformed, is supplied to the HOT surface of the power
generating element 110. However, the area to which the heat is
supplied is the area corresponding to the width of the first heat
storing plate 111. To make the description easier to understand,
both of the first heat storing plate 111 and the second heat
storing plate 112 have the same width (area) and the half width
(area) of the heat storing plate 200 but are not limited
thereto.
Incidentally, the first heat storing plate 111 and the second heat
storing plate 112 are not in contact with each other. However, when
the second heat storing plate 112 and the power generating element
110 are connected (switch closed), the heat transferred from the
first heat storing plate 111 and the second heat storing plate 112
is uniformed at the HOT surface of the power generating element
110. Therefore, when the second heat storing plate 112 and the
power generating element 110 are connected, the temperature and the
transfer range of the heat transferred to the HOT surface of the
power generating element 110 are the same as those in illustrated
in FIG. 6.
Next, the generated power of the power generating element 110 in
the conditions described for FIG. 6 and FIG. 7 are described with
reference to FIG. 8. FIG. 8 is a graph illustrating generated power
of the power generating element 110.
In FIG. 8, the graph shows the relation between the temperature
difference T (X axis) of the HOT surface and the COLD surface of
the power generating element 110 and the generated power (Y axis)
per unit area thereof and the conditions described for FIG. 6 and
FIG. 7 are plotted in the graph. The unit area here represents an
area receiving the heat from a single piece of the first heat
storing plate 111 (same as the second heat storing plate 112). In
addition, in FIG. 8, the temperature of the COLD surface is 60
degrees C. 60 degrees C. is kept in the image forming apparatus 10
by the cooler 113.
In general, the generated power per unit area in the power
generating element 110 increases directly with the square of the
temperature difference T as indicated in this graph. In the
condition of FIG. 7, since the temperature difference T is 150
degrees C. (210 degrees C. minus 60 degrees C.), the generated
power per unit area is 90 W as indicated by the point Bp.
In the condition of FIG. 6, since the temperature difference T is
100 degrees C. (160 degrees C. minus 60 degrees C.), the generated
power per unit area is 40 W as indicated by the point Ap'. However,
in the condition of FIG. 6, the area in which the power generating
element 110 is capable of generating power is twice as large as in
FIG. 7 reflecting the area of the heat storing plates serving as
the heat transfer source. Therefore, the generated power of the
entire of the power generating element 110 is 80 W (40.times.2) as
indicated by the point Ap.
When both are compared, a larger generated power is obtained in the
condition of FIG. 7. That is, it is found that a larger generated
power is obtained by dividing a heat storing plate and separating
one of the divided plate from the power generating element 110
although the area capable of generating power is smaller. This is
because, according to the relation of the square proportion between
the temperature difference T and the generated power, the generated
power is larger in some cases when the power is generated by
storing heat from the portion having a large temperature difference
T in a concentration manner.
Taking into account what is described above, the state of heat
supply to the power generating element 110 in various situations in
the image forming apparatus of an embodiment of the present
disclosure are described. Incidentally, the structure and
conditions of each part illustrated in the figures later
corresponding to FIG. 7 illustrating the state of heat supply to
the power generating element 110 are the same as those in FIG. 7
unless otherwise specified. The conditions different from those in
FIG. 7 are specified in each occasion.
First, the state of heat supply to the power generating element 110
when the image forming apparatus 10 stands by is described with
reference to FIG. 9 and FIG. 10. The difference between FIG. 9 and
FIG. 10 is whether the second heat storing plate 112 is separated
from or connected with the power generating element 110. FIG. 9
illustrates the case in which these are separated and FIG. 10
illustrates the case in which these are connected.
In addition, in FIG. 9 and FIG. 10, the temperature distribution
profile of the surface of the fixing roller 107a is represented by
the solid line C. Unlike the case in FIG. 7, since the image
forming apparatus 10 is stands by, the temperature of the fixing
roller 107a is relatively low and 100 degrees C. in the entire
area.
In addition, in FIG. 9, the dotted line Ct1 indicates the
temperature of the heat transferred to the HOT surface of the power
generating element 110 when the first heat storing plate 111 is
moved closer to the fixing roller 107a in the state indicated by
the solid line C.
The first heat storing plate 111 deprives the portion of 100
degrees C. of heat and the heat of 100 degrees C. is transferred to
the HOT surface of the power generating element 110. On the other
hand, since the second heat storing plate 112 is separated from the
power generating element 110, the stored heat is not transferred to
the HOT surface of the power generating element 110.
In FIG. 10, the dotted line Ct2 indicates the temperature of the
heat transferred to the HOT surface of the power generating element
110 when the first heat storing plate 111 and the second heat
storing plate 112 are moved closer to the fixing roller 107a in the
state indicated by the solid line C.
The state of heat supply to the power generating element 110 by the
first heat storing plate 111 is the same as in FIG. 9. In addition,
since the second heat storing plate 112 is connected with the power
generating element 110, the stored heat of 100 degrees C. by the
second heat storing plate 112 is also transferred to the HOT
surface of the power generating element 110.
FIG. 11 is a graph to describe the generated power of the power
generating element 110 in the conditions described for FIG. 9 and
FIG. 10. The description of the FIG. 8 is applied to the graph.
In the condition of FIG. 9, since the temperature difference T is
40 degrees C. (100 degrees C. minus 60 degrees C.), the generated
power per unit area is 6.4 W as indicated by the point Cp1.
This is the same as in the conditions for FIG. 10. However, in FIG.
10, the area in which the power generating element 110 is capable
of generating power is twice as large as in FIG. 9 since the second
heat storing plate 112 is connected. Therefore, the generated power
of the entire of the power generating element 110 is 12.8 W
(6.4.times.2) as indicated by the point Cp2.
When both are compared, a larger generated power is obtained in the
condition of FIG. 10.
That is, when the temperature of the heat stored by the first heat
storing plate 111 and the second heat storing plate 112 is the
same, it is found that a larger generated power is obtained when
the first heat storing plate 111 and the second heat storing plate
112 are connected to increase the area in which the power
generating element 110 is capable of generating power.
Next, the state of heat supply to the power generating element 110
after the image forming apparatus 10 has printed images on 10 B5
transfer sheets is described with reference to FIG. 12 and FIG. 13.
FIG. 12 illustrates the case in which the second heat storing plate
112 is disconnected (separated) from the power generating element
110 and FIG. 13 illustrates the case in which these are
connected.
In addition, in FIG. 12 and FIG. 13, the reference numeral 220
indicates the position where the transfer sheet has passed during
printing and the solid line D indicates the temperature
distribution profile of the surface of the fixing roller 107a.
Since this example is after printing, the temperature of the range
through which the transfer sheets have passed is lower than the
other portions. The temperature distribution profiles in FIG. 12
and FIG. 13 are closer to the real situation than the case in FIG.
7. The temperature of the surface of the fixing roller 107a is 100
degrees C. at the position 220 where the transfer sheets have
passed, rises gradually toward the end portion, and 150 degrees C.
at both ends.
In FIG. 12, the dotted line Dt1 indicates the temperature of the
heat transferred to the HOT surface of the power generating element
110 when the first heat storing plate 111 is moved closer to the
fixing roller 107a in the state indicated by the solid line D.
The first heat storing plate 111 stores the heat from the portion
of the surface of the fixing roller 107a in a temperature range of
from about 125 degrees C. to about 150 degrees C. The heat of about
138 degrees C., which is the average of those temperatures, is
supplied to the power generating element 110. On the other hand,
since the second heat storing plate 112 is disconnected from the
power generating element 110, the stored heat is not transferred to
the HOT surface of the power generating element 110.
In FIG. 13, the dotted line Dt2 indicates the temperature of the
heat transferred to the HOT surface of the power generating element
110 when the first heat storing plate 111 and the second heat
storing plate 112 are moved closer to the fixing roller 107a in the
state indicated by the solid line D.
The state of heat supply to the power generating element 110 by the
first heat storing plate 111 is the same as in FIG. 12. The first
heat storing plate 112 stores the heat from the portion of the
surface of the fixing roller 107a in a temperature range of from
about 100 degrees C. to about 125 degrees C. In addition, since the
second heat storing plate 112 is connected with the power
generating element 110, the heat of about 113 degrees C., which is
the average of those temperatures, is supplied to the HOT surface
of the power generating element 110.
In the HOT surface of the power generating element 110, as in the
case illustrated in FIG. 7, the heat transferred from the first
heat storing plate 111 and the heat transferred from the second
heat storing plate 112 are averaged. As a whole, the heat of the
average temperature 125 degrees C. is transferred to the HOT
surface of the power generating element 110.
FIG. 14 is a graph to describe the generated power of the power
generating element 110 in the conditions described for FIG. 12 and
FIG. 13. The description of the graph is the same as for FIG.
8.
In the condition of FIG. 12, since the temperature difference T is
78 degrees C. (138 degrees C. minus 60 degrees C.), the generated
power per unit area is 24 W as indicated by the point Dp1.
In the condition of FIG. 13, since the temperature difference T is
65 degrees C. (125 degrees C. minus 60 degrees C.), the generated
power per unit area is 17 W as indicated by the point Dp2'.
However, in FIG. 13, the area in which the power generating element
110 is capable of generating power is twice as large as in FIG. 12
since the second heat storing plate 112 is connected. Therefore,
the generated power of the entire of the power generating element
110 is 34 W (17.times.2) as indicated by the point Dp2.
When both are compared, a larger generated power is obtained in the
condition of FIG. 13.
That is, when the temperature of the heat stored by the first heat
storing plate 111 is not so much higher than the temperature of the
heat stored by the second heat storing plate 112, it is found that
a larger generated power is obtained when the second heat storing
plate 112 is connected with the power generating element 110.
Next, the state of heat supply to the power generating element 110
after the image forming apparatus 100 has printed images on 10 B5
transfer sheets is described with reference to FIG. 15 and FIG. 16.
FIG. 15 illustrates the case in which the second heat storing plate
112 is disconnected (separated) from the power generating element
110 and FIG. 16 illustrates the case in which these are
connected.
In addition, in FIG. 15 and FIG. 16, the reference numeral 220
indicates the position where the transfer sheets have passed during
printing and the solid line E indicates the temperature
distribution profile of the surface of the fixing roller 107a.
Since this example is also after printing, the temperature of the
range through which the transfer sheets have passed is lower than
the other portions. In addition, since the run length is more than
in the case of FIG. 12 or FIG. 13, the temperature difference
between the area through which the transfer sheets have passed and
the other portions is large and the temperature gradient is steep.
That is, the temperature of the surface of the fixing roller 107a
is 100 degrees C. at the position 220 where the transfer sheets
have passed, rises gradually toward the end, and 250 degrees C. at
both ends.
In FIG. 15, the dotted line Et1 indicates the temperature of the
heat transferred to the HOT surface of the power generating element
110 when the first heat storing plate 111 is moved closer to the
fixing roller 107a in the state indicated by the solid line E.
The first heat storing plate 111 stores the heat from the portion
of the surface of the fixing roller 107a in a temperature range of
from about 175 degrees C. to about 250 degrees C. The heat of about
225 degrees C., which is the average of those temperatures, is
supplied to the power generating element 110. On the other hand,
since the second heat storing plate 112 is disconnected from the
power generating element 110, the stored heat is not transferred to
the HOT surface of the power generating element 110.
In FIG. 16, the dotted line Et2 indicates the temperature of the
heat transferred to the HOT surface of the power generating element
110 when the first heat storing plate 111 and the second heat
storing plate 112 are moved closer to the fixing roller 107a in the
state indicated by the solid line E.
The state of heat supply to the power generating element 110 by the
first heat storing plate 111 is the same as in FIG. 15. The first
heat storing plate 112 stores the heat from the portion of the
surface of the fixing roller 107a in a temperature range of from
about 100 degrees C. to about 175 degrees C. In addition, since the
second heat storing plate 112 is connected with the power
generating element 110, the heat of about 125 degrees C., which is
the average of those temperatures, is supplied to the HOT surface
of the power generating element 110.
In the HOT surface of the power generating element 110, as in the
case illustrated in FIG. 7, the heat transferred from the first
heat storing plate 111 and the heat transferred from the second
heat storing plate 112 are averaged. As a whole, the heat of the
average temperature 175 degrees C. is transferred to the HOT
surface of the power generating element 110.
FIG. 17 is a graph to describe the generated power of the power
generating element 110 in the conditions described for FIG. 15 and
FIG. 16. The description of the graph is the same as for FIG.
8.
In the condition of FIG. 15, since the temperature difference T is
165 degrees C. (225 degrees C. minus 60 degrees C.), the generated
power per unit area is 110 W as indicated by the point Ep1.
In the condition of FIG. 16, since the temperature difference T is
115 degrees C. (175 degrees C. minus 60 degrees C.), the generated
power per unit area is 53 W as indicated by the point Dp2'.
However, in FIG. 16, the area in which the power generating element
110 is capable of generating power is twice as large as in FIG. 15
since the second heat storing plate 112 is connected. Therefore,
the generated power of the entire of the power generating element
110 is 106 W (53.times.2) as indicated by the point Ep2.
When both are compared, a larger generated power is obtained in the
condition of FIG. 15.
That is, when the temperature of the heat stored by the first heat
storing plate 111 is higher than the temperature of the heat stored
by the second heat storing plate 112, it is found that a larger
generated power is obtained when the second heat storing plate 112
is disconnected with the power generating element 110 to increase
the area in which the power generating element 110 is capable of
generating power.
That is, when the temperature of the heat stored by the first heat
storing plate 111 is sufficiently high in comparison with the
temperature of the heat stored by the second heat storing plate
112, the generated power is larger when the second heat storing
plate 112 is disconnected from the power generating element 110. In
addition, in the other cases, the generated power is larger when
the second heat storing plate 112 is connected with the power
generating element 110.
The factor having an impact on the temperature distribution profile
of the fixing roller 107a is not limited to the run length of a
print job. For example, the width of transfer paper has an impact
on the profile. Next, this point is described.
First, the state of heat supply to the power generating element 110
after a preset number of B5 transfer sheets with a portrait
orientation are used for printing is described with reference to
FIG. 18 and FIG. 19. FIG. 18 is a diagram illustrating a case in
which the second heat storing plate 112 is disconnected with the
power generating element 110 and FIG. 19 is a diagram illustrating
a case in which these are connected. In addition, in FIG. 18 and
FIG. 19, the reference numeral 220 indicates the position where the
transfer sheets have passed during printing and the solid line F
indicates the temperature distribution profile of the surface of
the fixing roller 107a.
Since this example is also after printing, the temperature of the
range through which the transfer paper has passed is lower than the
other portions. FIG. 18 and FIG. 19 represent schematic profiles as
in the case illustrated in FIG. 7 to make the difference of the
power generation efficiency by the size of transfer paper easily
understood. The temperature sharply changes between the low
temperature portion (110 degrees C.) in the range through which the
transfer paper has passed and the other high temperature portion
(210 degrees C.).
In addition, in FIG. 18, the dotted line Ft1 indicates the
temperature of the heat transferred to the HOT surface of the power
generating element 110 when the first heat storing plate 111 is
moved closer to the fixing roller 107a in the state indicated by
the solid line F.
The first heat storing plate 111 deprives the high temperature
portion having 210 degrees C. of heat and this heat is transferred
to the HOT surface of the power generating element 110. On the
other hand, since the second heat storing plate 112 is disconnected
with the power generating element 110, the stored heat is not
transferred to the HOT surface of the power generating element
110.
In FIG. 19, the dotted line Ft2 indicates the temperature of the
heat transferred to the HOT surface of the power generating element
110 when the first heat storing plate 111 and the second heat
storing plate 112 are moved closer to the fixing roller 107a in the
state indicated by the solid line F.
The state of heat supply to the power generating element 110 by the
first heat storing plate 111 is the same as in FIG. 19. In
addition, the second heat storing plate 112 is connected and stores
the heat from the high temperature portion having 210 degrees C.
like the first heat storing plate 111. This heat is transferred to
the HOT surface of the power generating element 110. In the HOT
surface of the power generating element 110, the heat transferred
from the first heat storing plate 111 and the heat transferred from
the second heat storing plate 112 are averaged. As a whole, the
heat of the average temperature 210 degrees C. is transferred to
the HOT surface of the power generating element 110.
FIG. 20 is a graph to describe the generated power of the power
generating element 110 in the conditions described for FIG. 18 and
FIG. 19. The description of the FIG. 8 is applied to the graph.
In the condition of FIG. 18 and FIG. 19, since the temperature
difference T is 150 degrees C. (210 degrees C. minus 60 degrees
C.), the generated power per unit area is 90 W as indicated by the
point Fp1.
However, in FIG. 19, the area in which the power generating element
110 is capable of generating power is twice as large as in FIG. 18
since the second heat storing plate 112 is connected. Therefore,
the generated power of the entire of the power generating element
110 is 180 W (90.times.2) as indicated by the point Fp1'.
Therefore, the generated power is found to be larger when the
second heat storing plate 112 is connected with the power
generating element 110.
Next, the state of heat supply to the power generating element 110
after a preset number of A4 transfer sheets with a portrait
orientation are used for printing is described with reference to
FIG. 21 and FIG. 22. FIG. 21 is a diagram illustrating a case in
which the second heat storing plate 112 is disconnected with the
power generating element 110 and FIG. 22 is a diagram illustrating
a case in which these are connected. In addition, in FIG. 21 and
FIG. 22, the reference numeral 210 indicates the position where the
transfer sheet has passed during printing and the solid line G
indicates the temperature distribution profile of the surface of
the fixing roller 107a.
Since this example is also after printing, the temperature of the
range through which the transfer sheet has passed is lower than the
other portions. FIG. 21 and FIG. 22 represent schematic profiles as
in the case illustrated in FIG. 7. The temperature sharply changes
between the low temperature portion (110 degrees C.) in the range
through which the transfer paper has passed and the other high
temperature portion (210 degrees C.)
In addition, in FIG. 21, the dotted line Gt1 indicates the
temperature of the heat transferred from the HOT surface of the
power generating element 110 when the first heat storing plate 111
is moved closer to the fixing roller 107a in the state indicated by
the solid line G.
The first heat storing plate 111 deprives the high temperature
portion having 210 degrees C. of heat and this heat is transferred
to the HOT surface of the power generating element 110. On the
other hand, since the second heat storing plate 112 is disconnected
with the power generating element 110, the stored heat is not
transferred to the HOT surface of the power generating element
110.
In FIG. 22, the dotted line Gt2 indicates the temperature of the
heat transferred to the HOT surface of the power generating element
110 when the first heat storing plate 111 and the second heat
storing plate 112 are moved closer to the fixing roller 107a in the
state indicated by the solid line G.
The state of heat supply to the power generating element 110 by the
first heat storing plate 111 is the same as in FIG. 21. In
addition, the second heat storing plate 112 is connected and stores
the heat from the high temperature portion having 110 degrees C.
This heat is transferred to the HOT surface of the power generating
element 110. In the HOT surface of the power generating element
110, the heat transferred from the first heat storing plate 111 and
the heat transferred from the second heat storing plate 112 are
averaged. As a whole, the heat of the temperature 160 degrees C. is
transferred to the HOT surface of the power generating element
110.
FIG. 23 is a graph illustrated to describe the generated power of
the power generating element 110 in the conditions described for
FIG. 21 and FIG. 22. The description of the FIG. 8 is applied to
the graph.
In the condition of FIG. 21, since the temperature difference T is
150 degrees C. (210 degrees C. minus 60 degrees C.), the generated
power per unit area is 90 W as indicated by the point Gp1.
In the condition of FIG. 22, since the temperature difference T is
100 degrees C. (160 degrees C. minus 60 degrees C.), the generated
power per unit area is 40 W as indicated by the point Gp2'.
However, in FIG. 22, the area in which the power generating element
110 is capable of generating power is twice as large as in FIG. 23
since the second heat storing plate 112 is connected. Therefore,
the generated power of the entire of the power generating element
110 is 80 W (40.times.2) as indicated by the point Gp2.
Therefore, the generated power is found to be larger when the
second heat storing plate 112 is disconnected with the power
generating element 110.
When the two examples are compared, it is found that whether the
second heat storing plate 112 is connected or disconnected with the
power generating element 110 depends on the width of transfer paper
for use in printing.
Both the run length for printing described above and the width of
transfer paper are included in the print setting information
indicating the content of a print job to be executed. Therefore,
for every content (classified into multiple classes for each
parameter) of print setting information, the temperature
distribution profile of the fixing roller 107a after executing the
print job of the content is stored in the image forming apparatus
10 in advance. Thereafter, when executing the print job, whether
the second heat storing plate 112 and the power generating element
110 is connected or disconnected is controlled based on the
temperature distribution profile linked with the print setting
information for the print job. This is described next.
FIG. 24 is a table illustrating a storage state of the temperature
distribution profiles in the image forming apparatus 10.
As illustrated in the table, the image forming apparatus 10 stores
the temperature distribution profile of the fixing roller 107a of
an executed print job in the memory 116 in advance while pairing
with the content of the print setting information.
In FIG. 24, for example, the profile X10 includes information
indicating the temperature distribution of the fixing roller 107a
after executing a print job of B5 size transfer paper with a
portrait orientation and a run length of 1 to 10 sheets.
Incidentally, to be exact, the temperature distribution linked with
a run length of a single sheet is different from for a run length
of 10 sheets and also the temperature distribution depends on the
surrounding environment in some degree. However, it is suitable to
divide data into groups each having a certain pieces taking into
account amount of data and store the average value of each
group.
The control device 115 reads out such a temperature distribution
profile and calculates a predicted generated power value to control
connection and disconnection of the second heat storing plate
112.
The processing about switch control of connection and disconnection
of the second heat storing plate 112 is described next, which is
executed by the control device 115 (actually, the processor
included therein) of the image forming apparatus 10. FIG. 25 is a
flow chart illustrating this processing. This processing relates to
embodiment of the image forming method of the present
disclosure.
The control device 115 initiates the execution of the processes of
the flow chart illustrated in FIG. 25 when the image forming
apparatus 10 is started (for example, the time of power-on,
resetting).
In the processing illustrated in FIG. 25, the control device 115
controls a switch 112a to connect the second heat storing plate 112
with the power generating element 110 (S21). The image forming
apparatus 10 normally stands by first after power-on. While it
stands by, the obtained generated power is expected to be greater
when the second heat storing plate 112 is connected as described
above with reference to FIG. 9 to FIG. 11.
Thereafter, the control device 115 stands by until it detects an
instruction of executing a print job has been input into the image
forming apparatus 10 (S22).
Thereafter, if yes to the step S22, the control device 115 acquires
the print setting information based on the content of the detected
instruction of executing the print job (S23). The print setting
information includes requisites for printing such as the size and
orientation of transfer paper, run length, color or monochrome.
This processing is an acquisition procedure and the control device
115 functions as an acquisition device in this processing.
Thereafter, based on the acquired print setting information, the
control device 115 reads out the temperature distribution profile
that corresponds to the print setting information of the multiple
temperature distribution profiles stored in the memory 116 as
illustrated in FIG. 18 (S24). Then, based on the temperature
distribution profile read out, the control device 115 calculates
the expected value of the generated power of the power generating
element 110 as the prediction value when the second heat storing
plate 112 is disconnected with the power generating element 110 and
when the second heat storing plate 112 is connected with the power
generating element 110 (S25).
The expected value of the generated power is calculated using the
following calculation method.
That is, the expected value W1 of the generated power when the
second heat storing plate 112 is disconnected and the expected
value W2 of the generated power when the second heat storing plate
112 is connected are represented by the following relations.
W1=.alpha..times.(Touthot-Tcold).sup.2
W2=.alpha..times.{(Touthot+Tinhot)/2-Tcold)}.sup.2.times.2
In the relations, a represents a proportionality coefficient,
Touthot represents the temperature (averaged temperature)
transferred from the first heat storing plate 111 to the HOT
surface of the power generating element 110, Tinhot represents the
temperature (averaged temperature) transferred from the second heat
storing plate 112 to the HOT surface of the power generating
element 110, and Tcold represents the temperature of the COLD
surface of the power generating element 110 (the surface
temperature of the COLD surface is considered to be uniform).
Next, the control device 115 determines which of the expected
values W1 and W2 is larger (S26).
When W1 is larger than W2 (yes to S26), the control device 115
controls the switch 112a to disconnect the second heat storing
plate 112 with the power generating element 110 (S27). When W2 is
larger than or equal to W1 (no to S26), the control device 115
controls the switch 112a to connect the second heat storing plate
112 with the power generating element 110 (S28).
In both cases, thereafter the control device 115 starts the print
job according to the instruction detected at Step S22 (S29).
This processing in Step S26 to S28 is a control procedure and the
control device 115 functions as a control device in this
processing.
Thereafter, the control device 115 stands by until a predetermined
time period elapses after the initiated print job is complete (yes
to S30) or another instruction of executing the next print job is
detected (yes to S31). When the predetermined time period elapses,
the control device 115 returns to Step S21 and repeats the
processing. When the instruction of the next print job is detected,
the control device 115 executes the processing of Step S23 and
thereafter.
The temperature distribution profile read out at Step S24 indicates
the state of the fixing roller 107a after executing the print job
according to the print setting information acquired at Step
S23.
This control following the temperature distribution profile mainly
aims to increase the generated power in a certain period of time
from the completion of a print job to when the temperature of the
fixing roller 107a entirely falls.
After this certain period of time elapses and the next print job is
not detected, the temperature of the fixing roller 107a gradually
falls. Therefore, since it is inferred that a larger generated
power is obtained by connecting the second heat storing plate 112
with the power generating element 110, this connection is made at
Step S21.
On the other hand, if an instruction of executing the next print
job is detected, the control device 115 controls according to the
print setting information for use in the print job.
The control device 115 is executing this processing illustrated in
FIG. 25 while the power of the image forming apparatus 10 is
on.
By the processing illustrated in FIG. 25 described above, the
control device 115 suitably controls connection and disconnection
between the second heat storing plate 112 and the power generating
element 110 according to the content of a print job to be executed
which is assigned by the print setting information. For this
reason, the power generating element 110 can be operated at a high
power generation efficiency even when the temperature of the fixing
roller 107a is not uniform and its distribution varies depending on
the situation.
In addition, since the control device 115 predicts which generated
power is higher when connected or disconnected using the
temperature distribution profile stored in advance pairing with the
print setting information, the control can be conducted with little
processing load.
In the present disclosure, specific configurations, of apparatuses
including the fixing device, the configuration and arrangement of
the heat storing plates, articles of the print setting information
to be referred, the specific procedure of the processing, and the
thresholds are not limited to those described in the
embodiments.
For example, the number of heat storing plates is not limited to
two, which is described in the embodiments described above. Also,
the size of the heat storing plates is not necessarily the same.
There is no need to provide the same number of heat storing plates
at both ends. Moreover, if it is possible to switch connection and
disconnection between at least one of heat storing plates and a
generating element, similar effects can be more or less obtained
within the scope of the effect described above. Furthermore, the
heat storing plate does not necessarily take a plate-like form.
The effect of making connection and disconnection switchable is to
increase the amount of generated power by increasing the
temperature difference of the HOT surface and the COLD surface of a
power generating element by not storing heat from a low temperature
area. Accordingly, it is suitable to make switchable connection and
disconnection between a power generating element and a heat storing
plate (the second heat storing plate 112 in the embodiments
described above) that may have a lower temperature than other
portions depending on the situation. With regard to the first heat
storing plate 111, since it is provided to the place whose
temperature does not easily fall in comparison with other portions,
the plate 111 is always connected with the power generating element
110. However, it can be made switchable depending on the cost,
etc.
In addition, it is possible to pair the temperature distribution
profile of the fixing roller 107a with the amount of toner for use
in an image fixed on a recording medium (transfer paper) instead of
or in addition to the print setting information. This is because if
a large amount of toner is used for an image, the fixing roller
107a is deprived of heat accordingly so that the temperature
thereof is considered to fall. In addition, the toner amount on
transfer paper can be deduced by counting the number of dots (black
or color) based on the image data of an image formed on the
transfer paper.
In this case, as illustrated in FIG. 26, the temperature
distribution profile of the fixing roller 107a can be stored for
each combination of the print setting information and the amount of
toner. In addition, in the processing of Step S23 illustrated in
FIG. 25, the amount of toner on transfer paper is deduced based on
image data of an image formed on the transfer paper for a detected
print job and thereafter the temperature distribution profile
combined with the print setting information and the amount of toner
is read out. Thereafter, according to this temperature distribution
profile, each of the expected value W1 of the generated power and
the expected value W2 of the generated power is calculated for the
next processing.
In such a case, the temperature distribution of the power
generating element 110 is appropriately predicted based on the
content of image forming and the power generating element 110 can
be operated with a high power generation efficiency even when the
temperature of the fixing roller 107a is not uniform and its
distribution varies depending on the situation.
In addition, it is also appropriate to store the temperature
distribution profile of the fixing roller 107a linked with the
print setting information not only at the completion of a print job
but also at every certain time elapse interval. This is because if
the temperature of the portion corresponding to the first heat
storing plate 111 is higher than the other portions and
disconnecting the second heat storing plate 112 with the power
generating element 110 is preferable, it is inferred that the
temperature entirely falls and the temperature difference decreases
as the time passes so that connecting both is preferable at some
point in time.
In this case, as illustrated in FIG. 27, it is suitable to store
the temperature distribution profile of the fixing roller 107a for
each combination of the print setting information and the elapsed
time after the print job is complete. In the processing of Step S24
illustrated in FIG. 25, it is suitable to read out the print
setting information and the temperature distribution profile of
each elapsed time corresponding to the amount of toner and
calculate each of the expected values of the generated power W1 and
W2 for each elapsed time. The time when W1 is equal to or shorter
than W2 is determined as the certain time of period for use in Step
S30. If W1 is equal to or shorter than W2 in the beginning, the
certain time of period can be set zero.
In such a case, the power generating element 110 can be operated
with a high power generation efficiency considering the change over
time of the temperature even when the temperature of the fixing
roller 107a is not uniform and its distribution varies depending on
the situation.
In addition, it is thinkable to provide multiple heaters having
different heating ranges as the heater 107b to heat the fixing
roller 107a. For example, it is possible to provide a heater to
mainly heat portions in the vicinity of the end and a heater to
heat portions around the center.
In this case, the temperature distribution profile of the fixing
roller 107a is likely to be different depending on which heater is
used. Therefore, as illustrated in FIG. 28, it is appropriate to
store the temperature distribution profile linked with the
combination of the print setting information and the usage status
of each heater. The usage status relates to, for example, the
output, the rate, the power-on time of each heater.
In the processing illustrated in FIG. 25, it is suitable to acquire
the temperature distribution profile corresponding to the usage
status (and the print setting information of the print job in
execution) of a heater at the completion of the print job or any
time during execution to calculate the expected values of the
generated power W1 and W2 based on the temperature profile. When W1
is greater than W2, it is suitable to disconnect the second heat
storing plate 112 with the power generating element 110.
In addition, in the processing illustrated in FIG. 25, it is also
possible to read out not only the temperature distribution profile
at the start of a print job but also the temperature distribution
profile corresponding to the execution state of the print job up to
any given time during the execution of the print job to calculate
the expected values of the generated power W1 and W2 and control
connection and disconnection of the second heat storing plate 112
depending on the relation of the expected values. For example, when
executing a print job with a run length of 100 sheets of transfer
paper, the connection and disconnection can be controlled based on
the temperature distribution profile corresponding to the case in
which the run length is ten sheets of transfer paper at the time of
completing printing on the tenth transfer paper and the temperature
distribution profile corresponding to the case in which the run
length is 20 sheets of transfer paper at the time of completing
printing on the 20th transfer paper.
In such a case, when the fixing roller 107a is heated by multiple
heating devices (heaters), it is possible to operate the power
generating element 110 with a high power generation efficiency
according to the usage status of the heating devices.
Incidentally, in any case, it is not necessary to refer all of the
size and orientation of transfer paper and the run length, or other
articles can be referred.
In addition, instead of storing the temperature distribution
profile in the image forming apparatus 10, it is possible to have a
switching configuration between connection and disconnection in
which the temperature to store heat in each condition, W1 or W2,
and whether each heat storing plate is connected or disconnected in
each condition are stored to be referred in the processing
illustrated in FIG. 25.
In addition, it is also appropriate to store a temperature
distribution profile or information instead thereof in a storage
device provided to a unit outside the image forming apparatus 10
and acquire the information from the unit on a necessity basis.
Furthermore, in the embodiments described above, the COLD surface
of the power generating element 110 is kept at 60 degrees C. by
using the cooler 113 but the temperature is not limited to 60
degrees C.
Moreover, the present invention can be applied to any image forming
apparatus forming images by a system other than electrophotography,
which includes a fixing device to fix an image on a recording
medium by heating the recording medium.
Furthermore, this can be applied to a heat source for a device
other than a fixing device when the temperature rises during image
forming if the temperature distribution profile of the heat source
is created and connection and disconnection to the heat source can
be set.
The description of embodiments of the present disclosure is
complete. In the present disclosure, specific configurations of
devices, specific configurations of the fixing device and the heat
storing member, and specific procedures of execution, etc. are not
limited to those described for the embodiments.
Moreover, in embodiments of the program of the present disclosure,
the function (mainly function of the acquisition device and the
control device) of the control device 115 described above is
executed by controlling hardware such as the image forming
apparatus 10 by a computer.
This kind of program can be stored in ROM inherently provided in a
computer or in a non-volatile storage medium such as flash memory
and EEPROM). However, it is also possible to record the program in
an arbitrary non-volatile recording medium such as memory card, CD,
DVD, and blu-ray disc. The program recorded in such a recording
medium is installed into a computer and executed thereby to execute
the above-mentioned procedures.
Furthermore, it is also possible to download the program from a
networked external device having a recording medium in which the
program is recorded or a networked exterior device having a storage
device in which the program is stored and install the program into
a computer for execution.
In addition, there is no limit to the combination of the
configurations of the embodiments and variations described above
unless mutual discrepancies occur.
Numerous additional modifications and variations are possible in
light of the above teachings. It is therefore to be understood that
within the scope of the appended claims, the disclosure of the
present invention may be practiced otherwise than as specifically
described herein. For example, elements and/or features of
different illustrative embodiments may be combined with each other
and/or substituted for each other within the scope of this
disclosure and appended claims.
Each of the functions of the described embodiments may be
implemented by one or more processing circuits or circuitry.
Processing circuitry includes a programmed processor, as a
processor includes circuitry. A processing circuit also includes
devices such as an application specific integrated circuit (ASIC)
and conventional circuit components arranged to perform the recited
functions.
The present invention can be implemented in any convenient form,
for example using dedicated hardware, or a mixture of dedicated
hardware and software. The present invention may be implemented as
computer software implemented by one or more networked processing
apparatuses. The network can comprise any conventional terrestrial
or wireless communications network, such as the Internet. The
processing apparatuses can compromise any suitably programmed
apparatuses such as a general purpose computer, personal digital
assistant, mobile telephone (such as a WAP or 3G-compliant phone)
and so on. Since the present invention can be implemented as
software, each and every aspect of the present invention thus
encompasses computer software implementable on a programmable
device. The computer software can be provided to the programmable
device using any storage medium for storing processor readable code
such as a floppy disk, hard disk, CD ROM, magnetic tape device or
solid state memory device.
The hardware platform includes any desired kind of hardware
resources including, for example, a central processing unit (CPU),
a random access memory (RAM), and a hard disk drive (HDD). The CPU
may be implemented by any desired kind of any desired number of
processor. The RAM may be implemented by any desired kind of
volatile or non-volatile memory. The HDD may be implemented by any
desired kind of non-volatile memory capable of storing a large
amount of data. The hardware resources may additionally include an
input device, an output device, or a network device, depending on
the type of the apparatus. Alternatively, the HDD may be provided
outside of the apparatus as long as the HDD is accessible. In this
example, the CPU, such as a cache memory of the CPU, and the RAM
may function as a physical memory or a primary memory of the
apparatus, while the HDD may function as a secondary memory of the
apparatus.
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